#include <iostream>

int main(int argc, char *argv[])
{
	std::cout << "Hello World" << std::endl;
	
	
	//计算乘法
	int v1 = 0;
	int v2 = 0;
	
	/// '<<'是运算符，运算符的左侧必须是 ostream 流，右侧是要输出的类型，运算符的结果是返回左侧的 ostream 对象。
	/// 所以 std::cout << v1 的返回结果可继续用于下一个 << 运算法
	/// std::cout << v1 << v2； 也就相当于
	/// (std::cout << v1) << v2;
	/// 两者是等价的
	
	std::cout << "请输入两个数字:" << std::endl;
	std::cin >> v1 >> v2;
	std::cout << "The * of " << v1 << " and " << v2 << " is " << v1*v2 << std::endl;
	
	
	//iostream, istream 输入流对象, ostream 输出流对象
	//C++标准库 iostream 库，已经提前定义了4个 iostream 流对象，istream对象 cin(发音see-in)， ostream对象 cout (发音see-out)
	//C++标准库 还定义了其它两个 ostream 对象 cerr 和 clog
	int v3 = 0;
	int v4 = 0;
	std::cout << "Please enter two number:";
	std::cout << std::endl;
	std::cin >> v3;
	std::cin >> v4;
	std::cout << "the number you enter is : ";
	std::cout << v3;
	std::cout << " ";
	std::cout << v4;
	std::cout << std::endl;
	std::cout << "the sum of ";
	std::cout << v3;
	std::cout << " and ";
	std::cout << v4;
	std::cout << " is ";
	std::cout << v3 + v4;
	std::cout << std::endl;
	
	///use cerr
	std::cerr << "Hello this is print out by C++ standart ostream object: cerr" << std::endl;
	
	/* this is a corrent comment */
	
	/* /* jieidngbu nenbug nei qinadtao */
	 * hello world 
	 *
	 *
	 */
	
	
	return 0;
}
